Site history: Chronic release of hazardous substances began in
the early 1900s.
Location: Castro Cove is a shallow, protected embayment of San
Pablo Bay (the northern portion of the greater San Francisco Bay estuary). The
cove is near the Chevron Refinery in Richmond, Contra Costa County, California.
At mean lower low water most of Castro Cove is exposed mudflat with areas of
intertidal salt marsh. Castro Cove is bordered to the east by Wildcat Marsh, a
large salt marsh, and to the west by the Contra County Sanitary Landfill. The
Chevron property forms most of the southern and western site boundary. Castro
Creek and Wildcat Creek enter the cove on the east and empty into a 30 – 75
foot-wide channel that transects a portion of the cove. Castro Cove is not
accessible to the public because it lies within the Chevron refinery property
and is generally not navigable.
Trustees:
Case status: Injury Assessment Phase.
Overview: Sediments in Castro Cove are contaminated from
historical discharges of wastewater and stormwater runoff from the Chevron
refinery and other sources. Between 1902 and 1987, Chevron and its predecessors
discharged refinery wastewater into to Castro Cove. Although Chevron relocated
the refinery’s wastewater outfall in 1987 to offshore in San Pablo Bay, high
levels of polycyclic aromatic hydrocarbons (PAHs) and mercury remain in
sediments, with the highest concentrations found in the southern portion of
Castro Cove near the old wastewater outfall.
Natural resources potentially injured include benthic invertebrates, fish,
mammals, and birds. Federally listed endangered and threatened species
that use Castro Cove include the salt marsh harvest mouse, clapper rail, and
steelhead.
The investigation and clean-up of Castro Cove is under the jurisdiction of the
California Regional Water Quality Control Board (Water Board); it is not a
federally listed Superfund site. In 1998, the Water Board requested that
Chevron prepare a Sediment Characterization Work Plan under the Bay Protection
and Toxic Cleanup Program. Several field investigation studies were conducted
between 1999 and 2001. Based on the results of these studies and the results of
benthic toxicity tests, approximately 20-acres of the intertidal mudflat in
Castro Cove was identified as the Area of Concern (AOC). Total PAHs have been
measured at a concentration as high as 507 mg/kg, and mercury as high as 13
mg/kg. A Corrective Action Plan (CAP) for sediment remediation in the AOC was
submitted to the Water Board in 2002 and revised and resubmitted in 2006. The
Water Board prepared a California Environmental Quality Act (CEQA) Mitigated
Negative Declaration, adopted the Corrective Action Plan, and issued a cleanup
order to Chevron in November 2006.
While the Water Board worked on site cleanup requirements, the natural resource
trustees initiated a natural resource damage assessment (NRDA). The goal of the
NRDA is to determine the type and amount of restoration required to restore
injured natural resources. Chevron agreed to work with the trustees in a
cooperative and expedited NRDA process.
The cleanup, scheduled for the summer of 2007, calls for the use of wet
dredging to remove contaminated sediments. The area will be isolated from the
rest of Castro Cove by a sheet pile enclosure (a temporary steel wall). Once
dredged, the sediment will be hydraulically pumped into an inactive treatment
pond located on the Chevron Richmond Refinery property. After dewatering the
sediments, they will be mixed with soils and a stabilizing agent such as cement
or fly ash. Then the surface of the inactive treatment pond area will be graded
and a vegetative cap will be installed.
